1. Technical Field
The present invention relates to tissue retractors, for use in medicine. More particularly, the present invention relates to fluid operated apparatus for use in moving apart abutting tissues, during surgery, in order to create a space between the tissues to improve visualization and for increased working space during open surgery and fiberoptic assisted surgery.
2. Description of the Prior Art
Current methods used for retracting tissue and improving visualization are mechanical separation using metal retractors during open surgery, or the direct pressure of an unconfined flow of fluid such as water or CO2 during fiberoptic surgery. A typical mechanical external fixator has pins driven through the bones and mechanically distracts the elements of the joint. Problems with the water method include fluid extravasation including into and through the tissue itself. Increased pressure and swelling result in the area, resulting in edematous or swollen tissue. Excess pressure from mechanical retractors may cause necrosis or tissue death. With these methods, it is impossible to monitor the pressure being applied to the body tissues, and tissue damage or necrosis can result.
While operating from within the body, i.e., fiber optic assisted surgery as opposed to open surgery, there is no known way to selectively move or retract tissue, either hard tissue such as bone or soft tissue, out of the way to improve visualization. No device in use adequately allows a surgeon to create an actual space or expand a potential space in the body, by separating adjacent layers of tissue. The prior art does not disclose a retractor that is powerful enough and made of a material that is strong and resilient enough to, for example, separate tissue planes from within. Such a device, especially in the field of fiber optic surgery, would allow a surgeon to visualize and operate without using the conventional bulky and awkward mechanical retractors that require large open incisions. Such a device would also permit working within the body without damaging a great deal of tissue in the path between the skin opening and the working area, by minimizing the external orifice or skin incision.
The present invention is a system of retractors that a surgeon can use to take potential spaces within the body and turn them into existing spaces safely and easily and controllably in order to safely visualize appropriate tissue and operate. The retractor selectively moves appropriate tissue out of the way to enable a surgeon to see and work better within the body, and selectively moves body parts such as joint parts or soft tissue planes in order to create a space between the tissues for visualization and for working.
The retractor of the present invention includes a fluid-operated portion such as a balloon or bladder to retract tissue, not merely to work in or dilate an existing opening as for example an angioscope does. The fluid-filled portion is flexible, and thus there are no sharp edges which might injure tissue being moved by the retractor. The soft material of the fluid-filled portion, to an extent desired, conforms to the tissue confines, and the exact pressure can be monitored so as not to damage tissue. The expanding portion is less bulky and more compact, and the pressure it applies at the tissue edges can stop bleeding of cut tissue. These are all features not possessed by a conventional mechanical retractor.
With a typical mechanical retractor, the opening in the skin and thence inwardly must be larger than the surgical area being worked upon, in order to be able to get the mechanical retractor into position. The surgeon must damage a large amount of tissue that may be healthy, in order to expose the tissue to be worked on. The retractor of the present invention minimizes damage to tissue in the way of the tissue the surgeon needs to expose, which was previously cut in a large open exposure. With the retractor of the present invention, the opening at the skin is smaller at the skin where the device is inserted, and wider at the location inside the body where the retractor is expanded. The retractor is first placed into the body in an unexpanded condition, and then, as it is expanded, pushes tissue out of the way in deeper layers of the body one can see and safely operate on affected tissue. Thus, less undesired tissue damage occurs.
The bladder is pressurized with air or with water or another fluid. The fluid used in the bladder must be safe if it accidentally escapes into the body. Thus, besides air, such other fluids as dextrose water, normal saline, CO2, and N2 are safe. The pressure in the bladder is monitored and regulated to keep the force exerted by the retractor at a safe level for tissue to prevent tissue necrosis. The retractor can exert a pressure on the tissues of as high as the mean diastolic pressure of 100 mm of mercury, or higher for shorter periods of time, while still being safely controlled. Typical inflatable devices such as angioscopes do not have anywhere near the strength, or the ability to hold enough fluid pressure, or shapes to retract tissue as described herein. As compared to prior art devices, the retractor of the present invention operates with greater pressure within the bladder, since it is made of stronger materials such as Kevlar or Mylar which may be reinforced with stainless steel, nylon, or other fiber to prevent puncturing and to provide structural shape and support as desired. Such materials are strong enough to hold the necessary fluid pressure of about several pounds or up to about 500 mg Hg or more and exert the needed force on the tissue to be moved. The choice of material is well within the ability of one familiar with such materials and accordingly will not be gone into in further detail herein. The present retractor is thus able to exert substantially more force on adjoining tissues than a prior art device. The shapes of the retractors are specific for each application, and may include separate variable chambers which are sequentially controllable, to control the direction of tissue retraction.
The fluid-filled portion of the retractor is preferably a unitary portion such as a bladder. In this case, the bladder is expanded with the introduction of fluid under pressure. Alternatively, the fluid-filled portion of the retractor may include a series of prongs or filaments that expand radially outwardly upon the introduction of fluid under pressure. The prongs themselves may be expandable, or there may be an expandable portion located centrally of all the prongs which, when it expands, forces the prongs outwardly.
Typically, the height of the bladder, that is, its width or transverse dimension, is significantly greater than its length (axial or longitudinal dimension). The bladder expands primarily in width only, not in length, although the shape will vary with the application. This is in accordance with the purpose of the device which is to enable the separation of adjacent tissue layers to, for example allow improved visualization in front of a scope inserted between the tissue layers.
The retractor of the present invention can be used to direct or position the end of a scope relative to the tissue walls. The retractor can also be used to stabilize the end of a scope. When a camera is being used via the scope, the scope often moves or jumps around because of the flexibility of the end of the scope. This is prevented by inflating bladders at the tip or along the shaft of the fiberoptic scope to control the direction of the tip of the scope and thus stabilize the scope, leaving both hands free to work and providing a stable image for the surgeon.
Surgeons operate along tissue planes. Once a surgeon finds a tissue plane, he dissects along it, starting the separation process with the knife. The retractor holds the tissue layers apart and helps and eases in defining and further separating the tissue layers as the surgeon operates along the tissue planes, helping to spread and define the planes. The retractor helps to separate the tissue layers, increasing the space for operating, and improving the surgeon""s ability to separate and visualize, leading to better and safer surgical technique.
A preferred use for the present retractor is in the field of fiber optic surgery, including endoscopy, arthroscopy, laparoscopy, etc. which require looking into and operating within a limited space with a fiber optic light and camera. The open or existing spaces in joints are generally too small to permit easy operation and visualization. In the Prior art, only direct (unconfined) water or air pressure is used to expand the joint capsule or tissue in the joint. This may actually push tissue in front of the scope, obscuring vision. The present retractor distracts a joint directly to make it easier to see inside (around) the joint. A sleeve which can be a malleable or rigid sheath may optionally be provided to protect the tissue as the bladder is slid in and out of the end of the cannula once in the work area within the joint. The bladder expands into an area of soft tissue-for example the bursa-and pushes it out of the way. The bladder can be left in place during the operation, or it can be deflated and removed, and the arthroscope and other instruments can be put into the space created.
An alternative preferred use for the retractor of the present invention is to operate in a joint of the spine, and specifically between two vertebrae. The retractor is used to spread two vertebrae apart to enable removal of the spinal disc from between the vertebrae.
Other uses of the retractor are as an occluding device to stop blood flow from an anastomosis or angioscopic procedure, or to stop backflow (retrograde flow) of stomach or colon contents. The retractor of the present invention is also suitable for use in the tempomandibular joint. Specifically, a dentist or oral surgeon uses an appropriately shaped retractor to hold open the jaw of a patient while the dentist or oral surgeon works on the mouth of the patient. The inflatable retractor is much more comfortable to the patient than a rigid metal or plastic device, it conforms to the jaw structure rather than pressing unevenly against it, and lessens fatigue. Thus it is safer for the dentist by safely maintaining the two rows of teeth spaced apart and by increasing visibility for working, while at the same time being easier for the patient.
The retractor can also be a useful diagnostic tool. The strength or pressure or resistance of tissue can be measured by the pressure required to move it.
The bladder may be a bellows type device in which the material does not stretch but which expands when pressurized from within and which is collapsed by the use of suction. In this case, it would preferably be made of a polymer of the class including Kevlar or Mylar fabric for strength and structural integrity. The bladder may generally also be made from any very thin walled polymer.
The bladder may also be made from a biocompatible and/or biodegradable material, so that if it can not be removed from the body for some reason, or if the surgeon desires to keep the bladder in place in the body for a period of time, it will not damage the tissue and may eventually be resorbed into the body. Such a biodegradable bladder may be left under the skin postoperatively to stop postoperative bleeding or to keep tissue expanded. Alternatively, the bladder may be made of a stretchable material which stretches when pressurized from within, and then collapses partially of its own accord when depressurized or also with the help of suction. The retractor may be transparent for better visibility, but it need not be for some applications. Also, the retractor can be disposable. The material choice is within the skill of the art. One surface of the bladder may be made of or have thereon a reflective surface to reflect light to see around a corner.
The retractor can be used as a joint jack that is, to distract a joint from within in one area and provide ease of access through the joint. Less damage to the joint occurs if the tissue edges are spaced apart during a procedure. When placed between two joint surfaces it pushes them apart from within, increasing the space available for visualization and/or the working space. The retractor stabilizes a joint when expanded because it forces the tissues to remain in one place.
Another use is to look directly at a neurovascular bundle, retract it out of the way, and then operate around it. For example, the surgeon can go into the back of a knee, inflate the retractor, identify the neurovascular bundle and then be able to work around it. The task is made easier by the ability to separate tissue layers from within. One may cup the tissue then push it out of the way, in the nature of an umbrella opening, to protect vital tissues to operate safely around them.
Depending on the application, the retractor can be left in place while the work (or looking) is being done, or it can be deflated and then taken out to allow a scope or other instrument to be put in. Some tissues will stay in place to allow this latter function, after the space has been created with the retractor.
A most typical construction for the retractor of the present invention is an inflatable bladder situated on the end of a shaft, which may be flexible or rigid, which is pushed through an extra opening in a scope or cannula or through a separate portal, and which expands at the end of the shaft.
The retractor can be located on a scope, either on the end thereof or movable axially through a channel along the length of the scope. The retractor can alternatively be mounted on a cannula. The retractor can be mounted on a separate shaft passing through an existing channel in a cannula; it can be inserted through a separate hole in the cannula or the scope; or it can be inserted through a separate opening in the body. The shaft with a retractor on the end can be pushed or slid through the cannula, side by side with a scope. Alternatively, the bladder can expand out of, then recess back into, a groove on a cannula or scope. The retractor can be used to create a space right from the end of the scope.
The bladder itself can be round, eccentric, oval, conical, wedge-shaped, U-shaped, curved, angled, or it may be in any shape desirable to optimize the particular application. The bladder may be irregularly shaped when inflated, that is, it may expand to a greater radius in the area where it is desired to look (where greater exposure space is needed).
Vacuum can be used to deflate the bladder. The bladder may then be removed by sliding it out the portal directly.
In one embodiment the retractor includes a spring loaded sleeve which slides axially over a plurality of plates or prongs, plastic or metal. A centrally located motive force is provided to move the prongs outwardly to retract the tissue, which force may be mechanical or a separate inflatable device. Alternatively, each filament is a tube which expands and straightens out as air pressure is added (as it is inflated) and thus moves radially outwardly to retract adjoining tissue. The filaments plates or prongs are controllable and covered by a sheath, which slides off them proximally axially to allow them to be inflated and expand, and then, after they have been deflated, slides distally along the shaft over the filaments to cover them and allow the device to be moved through the body. When the sleeve retracts the prongs or filaments expand radially outwardly to push tissue away from the scope to improve visualization.
The retractor can be disposed at the end of a flexible sheath. The retractor can be directable with cables, or with compressed air, to turn or bend in a certain direction.
The present invention also provides a new type of self-retaining retractor which is more compact and is disposable for use in open surgery. The retractor is used to hold tissues laterally, pushing tissue edges apart. For such an application, the retractor includes a U-shaped bladder which is a tube which acts like a spring and under high pressure attempts to straighten itself out when inflated. The deflated tube-like structure is first properly positioned within the wound. As the retractor is inflated, it tries to straighten out, and thus opens the wound, As it presses on the edges of the wound, it compresses tissue edges, giving a hemostatic effect. For example, if the retractor is put vertically into a wound, it expands the deep tissues. The retractor can also use the inflatable bladder to push apart metal or plastic plates to push apart tissue.